AIM: To describe the ambulatory changes in drug prescriptions 3 months after hospital discharge among elderly patients aged 75 and over, and to identify the reasons for these changes. METHODS: A prospective cohort study was conducted on subjects, discharged between 09/2016 and 01/2017 from the Bordeaux University Hospital. Prescription forms were collected from patients' pharmacists. The main outcome was the occurrence of at least one significant change (SC) defined as an initiation, a discontinuation, a switch or change in drug daily dosage as regards the drugs prescribed upon hospital discharge and those prescribed 3 months after. Whenever drug SC occurred, general practitioners were requested to elicit reasons for such changes. RESULTS: Among the 126 patients included in our study, 73 underwent a 3-month follow-up period, without death or being re-hospitalised. 87.7% of them had at least one SC 3 months after discharge, with an average of 3.1±2.5 SC per patient. Main changes involved: discontinuation or dose decrease of anxiolytics, hypnotics, antalgics, betablockers and calcium channel blockers; start or dose increase of diuretics, ACE inhibitors and angiotensin receptor blockers. In patients with a 3-month follow-up period, 27.4% underwent at least one ADR-induced SC. CONCLUSION: Most elderly patients experience drug prescription changes after discharge. Some, according to drug iatrogenic, could be avoided through better cooperation between hospital and ambulatory prescribers.Read less <